Straddle tool with disconnect between seals

ABSTRACT

A bottom hole assembly (BHA) enables a one trip procedure to set a bridge plug and release from that bridge plug with the BHA. A perforating gun is fired and a straddle tool above the gun in repositioned to wash the perforations as the opposed packer cups are moved along the perforations. At the end of the washing step a dropped ball closes a circulation port above the upper packer cups and the ball seat is blown out. A disconnect releases the lower part of the straddle tool with the lower packer cups that are uphole oriented. Cement can now be delivered past the upper packer cups and pressurized to squeeze the cement into the perforations using the upper cups to hold the pressure. Another ported sub above the upper cups has a port opened to prevent swabbing as the BHA is removed.

FIELD OF THE INVENTION

The field of the invention is methods for plugging and abandoning wells and more particularly methods that allow multiple operations in a single trip including among other steps running and setting a bridge plug, perforation, washing the perforations, delivering cement under pressure into the perforations and pulling the bottom hole assembly from the location without swabbing the well.

BACKGROUND OF THE INVENTION AND PROBLEMS RELATED THERETO

In many instances where a well has to be plugged and abandoned a series of steps are taken to build what amounts to a cement plug but the procedure has in the past been done in a series of discrete steps. One way was to run a perforating gun below a packer and fire the gun and inject cement into the newly created perforations as shown in U.S. Pat. No. 5,372,298. Pressure set washing tools for perforations are shown in U.S. Pat. No. 4,279,306. Systems that run a perforating gun between spaced plugs and release the lower plug to perforate and then set the upper plug to pump cement between the plugs is shown in GB 2414492 A1.

The plugging and abandonment requirements have changed over time and currently the basic steps are to set a bridge plug to act as a lower cement retainer and then perforate the cased hole. When perforating is complete the perforations have to be cleaned before the cement is delivered. The excess cement needs to be circulated out and it is preferred that the cement is squeezed into the perforations to anchor the plug that extends into the main bore. The perforating gun can either be dropped or retrieved before cementing. The bottom hole assembly used in the cement delivery then needs to be pulled out of the hole. While equipment exists to accomplish many of these tasks individually the use of discrete equipment for specific functions to be performed in a precise order has necessitated the use of multiple trips. Depending on the well depth and surface location these multiple trips necessitated additional rig time that as some locations can run up to hundreds of thousands of US dollars a day. Accordingly, there is a need for devices that facilitate moving from one procedure to the next in the same trip to save rig time and completion costs. Those skilled in the art will better appreciate the various aspects of the invention with regard to the equipment and methods that allow an array of completion procedures to be conducted in one trip from a review of the detailed description of the preferred embodiment and the associated figures while appreciating that the full scope of the invention is to be determined from the appended claims.

SUMMARY OF THE INVENTION

A bottom hole assembly (BHA) enables a one trip procedure to set a bridge plug and release from that bridge plug with the BHA. A perforating gun is fired and a straddle tool above the gun in repositioned to wash the perforations as the opposed packer cups are moved along the perforations. At the end of the washing step a dropped ball closes a circulation port above the upper packer cups and the ball seat is blown out. A disconnect releases the lower part of the straddle tool with the lower packer cups that are uphole oriented. Cement can now be delivered past the upper packer cups and pressurized to squeeze the cement into the perforations using the upper cups to hold the pressure. Another ported sub above the upper cups has a port opened to prevent swabbing as the BHA is removed.

The invention is a drill pipe string (11)-borne borehole assembly (10) comprising a washing tool assembly (18), comprising:

-   -   a main body (28) having an axial main bore passage (51) with one         or more laterally directed perforation wash ports (30), provided         with     -   one or more lower swab cups (24, 26) below and one or more upper         swab cups (34, 36) above said main body (28),     -   a lower ported sub (20) having at least one port (22) below said         lower swab cups (24, 26) and a bypass passage (42) to     -   an upper ported sub (38) with at least one port (40) above said         upper swab cups (34, 36),     -   characterized by     -   an actuated valve (381, 382) arranged for closing said one or         more upper port (40);         a disconnector (32) for said main body (28) including said main         bore passage (51) for forming a wide aperture (54) at a         remaining lower end of said disconnected main bore passage (51)         for pumping out cement.         The invention is also a method for plugging a cased petroleum         well comprising the steps of:

-   a) assembling on a drill pipe string (11) a borehole assembly (BHA)     (10) comprising     a bridge plug (12) on a plug setting tool (14) arranged below     perforation guns (16) further arranged below a wash tool assembly     (18) with a main bore (51) and with upper swab cups (34, 36) and     lower swab cups (24, 26) which are bypass ported by upper ports (38)     via a passage (42) to lower ports (22), and an intermediate ported     body (28) with wash ports (30) arranged for washing through     perforated casing,

-   b) running in said BHA (10) until said bridge plug (12) and said     perforation guns (16) are sufficiently below a zone in the casing to     be perforated,

-   c) setting and releasing said bridge plug (12),

-   d) positioning and firing said perforating guns (16) perforating     said zone of said casing,

-   e) positioning said wash tool assembly (18, 28, 30) and washing     behind said now perforated casing, and circulating out washed-out     debris,     characterized by

-   f) closing upper ports (40) in upper bypass port (38),

-   g) using a disconnector (32) arranged below said upper swab cups     (34, 36) and said upper ports (40, 38), of said wash tool assembly     (18), thereby disconnecting and releasing a lower half of said wash     tool assembly (18) with said perforating guns (16), so forming a     main bore (51) aperture (54) at or below an upper half of said     disconnector (32), and letting them drop,

-   h) pumping down cement via said main bore aperture (54), cementing     from a lower portion of said perforated range and continuing     upwardly until said perforated range is cemented.     Further advantageous features are defined in the attached dependent     claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is the run in position of the BHA of the invention;

FIG. 2 is the BHA of FIG. 1 in the position having set the plug, released the plug, perforated, washed behind casing and circulated out debris, split the wash tool and started conducting delivery of cement.

FIG. 3 illustrates a section of the BHA of the invention.

EMBODIMENTS OF THE INVENTION AND DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring to FIG. 1, the BHA 10 has a bridge plug 12 and an associated setting device 14 located above. The setting device 14 is preferably pressure operated against a seated ball (not shown) but other types of devices can be used without departing from the invention. A perforating gun 16 is mounted above the actuator followed by a wash tool assembly 18 that preferably has a lower ported sub 20 with ports 22 a pair of lower packer cups 24 and 26 followed by a ported body 28 with fluid outlets 30 for washing the perforations as will be explained below. A disconnect 32 is located immediately below the upper cups 34 and 36 which are both looking downhole. Cups 24 and 26 are looking uphole. Upper ported sub 38 has port openings 40 There is a flow passage 42 that runs between ports 22 and 40. Ports 40 can be selectively closed with an internal sliding sleeve associated with a ball seat that can shift the sleeve before the ball seal gets blown out for the purposes of delivering the cement or other sealing material as will be explained below. This internal assembly is not shown but it is of a type well known in the art. At the top of the BHA is another ported sub 44 that has a selectively opened port or ports 46 to allow circulating out of excess cement and to prevent well swabbing when pulling out of the hole by allowing fluid to bypass cups 34 and 36 on the trip out of the hole with the BHA 10 through now opened ports 46.

The one trip method works by virtue of running in the BHA 10 into a cased (11) hole, for example. The bridge plug 12 and its plug actuator 14 are placed far enough below the perforations to be made by the gun 16 so that when the gun 16 later is dropped, the gun 16 will be far enough below the perforations formed so as to not interfere with the step of washing through the perforations that comes later. When the bridge plug 12, which is of a type known in the art, is properly positioned the plug actuator 14 is energized, preferably with pressure, and the actuation of the plug also causes preferably a second disconnector (13) to release the actuator 14 from the gun 16 so that the BHA 10 can be repositioned to properly position the perforating gun 16 to one or more positions for conducting the perforation. When the gun 16 is properly positioned and set off to create the perforations the wash tool assembly is then positioned either near the top or near the bottom of the section of the casing wherin perforations have just been made by the gun 16, and the fluid from the surface is pumped through ports 30 that are between cups 26 and 34 such that pressure driven fluid at high velocity can be flushed out through the perforations to clean them and the annulus by removing debris from them with the fluid going into the perforations and coming out in the casing main bore either below cup 24 or above cup 36. The fluid that comes out below cup 24 may then enter ports 22 and pass up through passage 42 on the way to communicating with ports 40 that are above cup 36. It should be noted that the main bore passage (51) ends at ports 30 that before disconnection at disconnector (32) allows surface pumping to reach ports 30 for the washing procedure that preferably takes place as the BHA 10 moving axially in the borehole along the perforations. Again the direction of the washing tool assembly (18) can be top down or bottom up or any other pattern as long as the entire span of perforations gets exposed to the fluid jet stream that comes out of the ports 30.

At the conclusion of the washing of the perforation that is determined by a number of factors such as how many passes were made with the wash tool assembly 18, or the nature of the fluid that is returning, for example, the next big step is to pump cement or some other seal material. In order to do that two things occur. The ports 40 need to be closed and a large passage (54) needs to be opened for the pumped cement at a location where the pumped cement can be pressurized into the perforations after delivery. To do this the internal sleeve in sub 40 that is shifted by a ball landing on a seat where the seat gets blown out after shifting is actuated with pressure on the seated ball. The ports 40 are then closed and the passage for the cement is back to full bore (51) as the ball and seat have been blown out. Prior to the closing of ports 40 the disconnector 32 is actuated with internal pressure on another barrier that lands on a seat near disconnector 32. Thus, the order of operations is to part the disconnect 32 at a location between the cups 26 and 34 so that now the main passage (51) in the perforation wash tool 18 is open at aperture (54) through the now open upper half of disconnector 32, and the smaller ports 30 that directed the fluid jetting for cleaning the perforations do not have to conduct the cement or other seal material. FIG. 2 shows the disconnector (32) apart so that the guns 16 and lower cups 24 and 26 as well as the body of the tool 18 with the lower part of the disconnector 32 are dropped downhole onto the plug actuator 14. It should be mentioned again here that the perforation guns 16 were earlier released from the plug actuator 14 and raised before they got fired. Now with the disconnector (32) split, the guns 16 fall down to the actuator 14. The weight of the gun will contribute to pulls down the lower swab cups 24, 26).

Once the FIG. 2 position is obtained then the ports 40 are closed with the shifting of the internal sleeve and the blowing out of the ball seat with the ball, shown schematically in FIG. 2 as 48. Now the cement or other sealing material represented by arrow 50 can be pumped out through full-bore aperture (54) and the cement will be forced into the perforations 52. The lower cups 24 and 26, although earlier dropped still can act to stop the cement that falls down to fill the borehole. Alternatively the cement can go down to the bridge plug 12. The cups 34 or 36 can offer cement retention to pressures of about 5000 PSI to aid in forcing the cement represented by arrow 50 into the perforations. The closing of ports 40 forces the pressurized cement below the cups 34 and 36.

When the requisite volume of cement has been pumped or the pressure builds to a predetermined point indicating the perforations are full as is the bore the next step is to open ports 46 on pump out sub 44 so that excess cement can be circulated out. The opening of ports 46 also prevents well swabbing as flow from above cup 36 can get out below cup 34 through open end 52.

Optionally, at a later time if there is a desire to reopen the well, the cement in the borehole can be drilled out in a separate trip and a cement bond log can be run to determine the integrity of the cement in the perforations 52.

The tool 18 is moved as the cement is pumped out through the full-bore aperture (54) to push the cement into the entire interval. The bridge plug 12 is set far enough below the perforation so that when the disconnect 32 separates that portion of the BHA 10 that drops is still laying well below the perforations 52 so as to not interfere with subsequent cementing or later production from those perforations if they are to be reopened for any reason. Despite the separation between the cups 26 and 34 when the disconnect 32 is operated the upper cups 34 and 36 still function as a pressure retainer as does lower cup 26 backed up with cup 24. The tool 18 is unique in that it serves multiple function of jetting the perforations clean through ports 30 at high fluid velocities but is then reconfigured by coming apart at the disconnect (32) between opposed cups in such a way as to open the aperture (54) with a bigger flow channel (51) for the cement to shorten the cementing time and the pumping power required to deliver the cement. This tool 18 also has a bypass from above cup 36 at ports 40 through to below cup 24 at ports 22. This bypass is independent of the passage that directs wash fluid to ports 30 when tool 18 is intact and allows large bore flow of cement out lower end aperture (54) after the disconnect 32 is operated.

While packer cups are discussed as the seals other types of seals are envisioned such as inflatable or mechanically or hydraulically set resettable packers, for example. An advantage of the packer cups is that even when released they have a possibility to hold cement pressure and even if the lower cups 24 and 26 do not hold there is still the bridge plug (12) as a backup. While the tool 18 in the background art is illustrated in a plug and abandon method, the tool 18 has a new application wherein different flow regimes are needed for different functions at different times while saving a trip out of the hole to accomplish both functions.

Those skilled in the art will appreciate that the present one trip method is illustrated where a part of the well is isolated with a packer or bridge plug (12). The perforations are formed and then cleaned with a wash tool (18) that flushes fluid out through the perforations between spaced barriers, the lower and upper swab cups (24, 26, 34, 36) as the assembly (18) is moved to allow washing through all the perforations in a desired direction while providing a bypass path around the spaced isolators for return fluid to the surface around the tool interval between the spaced seals. The bypass (42) upper port (40) is then closed and the washing tool assembly (18) is split at the disconnector (32) between the seals to open a large flow passage (54) for the subsequent pumping out of cement with any potential bypass paths (40) around the top seals that remain with the BHA closed off The cement is squeezed out and through the perforations using the upper seals (34, 36) still with the BHA to retain pressure up to about 5000 PSI to ensure good cement penetration into the perforations. The lower seals even though dropped by the time cement is pumped, may still hold pressure but if they don't, the bridge plug is there for that purpose. The pump out sub is then activated and after picking up the excess cement can be circulated out and swabbing of the well is prevented because the open port on top of the upper seal can be a bypass through the upper packer cups because the path is open to lower end 54. 

1. A drill pipe string borne borehole assembly comprising a washing tool assembly, comprising: a main body having an axial main bore passage with one or more laterally directed perforation wash ports, provided with one or more lower swab cups below and one or more upper swab cups above said main body; a lower ported sub having at least one port below said lower swab cups and a bypass passage to an upper ported sub with at least one port above said upper swab cups, an actuated valve arranged for closing said one or more upper port; and a disconnector for said main body including said main bore passage for forming a wide aperture at a remaining lower end of said disconnected main bore passage for pumping out cement.
 2. The borehole assembly according to claim 1, further comprising a perforation gun arranged below said washing tool assembly.
 3. The borehole assembly of claim 2, comprising below said perforation gun a plug actuator arranged for setting a bridge plug in said casing, and a second disconnector arranged between said perforation gun and said plug.
 4. The borehole assembly of claim 3, said second disconnector arranged between said perforation gun and said plug actuator.
 5. The borehole assembly of claim 1, wherein said aperture is larger than said washing port.
 6. The borehole assembly of claim 1, wherein said disconnector is ball or pressure operated.
 7. The borehole assembly of claim 1, wherein said upper and lower swab cups are opposed in facing mirror image.
 8. The borehole assembly of claim 1, wherein said disconnector is arranged for releasing a portion of said body that includes said wash port and said lower swab cups to expose said aperture end of said main bore.
 9. The borehole assembly of claim 8, wherein said lower swab cups sealingly engage the casing after said disconnector has released to retain pressure against fluid delivered through said exposed aperture of said passage.
 10. The borehole assembly of claim 1, wherein said upper swab cups continue to engage the casing after said disconnector has released to retain pressure against fluid delivered through said exposed aperture of said passage.
 11. A method for plugging a cased petroleum well comprising the steps of: a) assembling on a drill pipe string a borehole assembly comprising a bridge plug on a plug setting tool arranged below perforation guns further arranged below a wash tool assembly with a main bore and with upper swab cups and lower swab cups which are bypass ported by upper ports via a passage to lower ports, and an intermediate ported body with wash ports arranged for washing through perforated casing; b) running in said BHA until said bridge plug and said perforation guns are sufficiently below a zone in the casing to be perforated, perforated; c) setting and releasing said bridge plug; d) positioning and firing said perforating guns perforating said zone of said casing; e) positioning said wash tool assembly and washing behind said now perforated casing, and circulating out washed-out debris; f) closing upper ports in upper bypass port; g) using a disconnector arranged below said upper swab cups and said upper ports, of said wash tool assembly, thereby disconnecting and releasing a lower half of said wash tool assembly with said perforating guns, so forming a main bore aperture at or below an upper half of said disconnector, and letting them drop; and h) pumping down cement via said main bore aperture, cementing from a lower portion of said perforated range and continuing upwardly until said perforated range is cemented.
 12. The method of claim 11, controlling one or more of said operations using pumped ball and seat release mechanisms and releasing said seats using pressure on shear pins of said seats.
 13. The method of claim 12, drilling through said cemented interval of said perforated casing and running a test log to verify the cementing, and cementing it.
 14. The borehole assembly of claim 2, wherein said aperture is larger than said washing port.
 15. The borehole assembly of claim 3, wherein said aperture is larger than said washing port.
 16. The borehole assembly of claim 4, wherein said aperture is larger than said washing port.
 17. The borehole assembly of claim 2, wherein said disconnector is ball or pressure operated.
 18. The borehole assembly of claim 3, wherein said disconnector is ball or pressure operated.
 19. The borehole assembly of claim 4, wherein said disconnector is ball or pressure operated.
 20. The borehole assembly of claim 5, wherein said disconnector is ball or pressure operated. 